High energy lasers (HELs) are becoming increasingly used in military applications as well as in industrial settings. HELs are commonly used in industrial processes, for example, to cut metals and other substances. When used as weapons, HELs are particularly useful in precision strike (PS) situations where it is desirable to minimize collateral damage. HELs have also been mounted on spacecraft, aircraft, ships and land-based vehicles for other military-related purposes, including missile defense.
One type of laser that is commonly used in military and industrial applications is the chemical oxygen iodine laser (COIL), which is typically a medium-power laser with a power on the order of about 100–200 kW. COIL lasers are typically fueled by reacting aqueous basic and hydrogen peroxide solution (BHP) with chlorine gas to form singlet delta oxygen (O2(1Δ)) or singlet molecular oxygen. For a laser using potassium as an alkali metal, the laser operates according to the following reaction:2KOH+H2O2+Cl2→2KCl+2H2O+O2(1Δ)  (1)
This excited state oxygen flows into a nozzle of the COIL laser where it reacts with iodine to form an excited state of the iodine atom, I*, which in turn acts as a gain medium to produce stimulated photon emissions and coherent light with a wavelength of about 1.315 μm. This emitted light can be focused and directed to produce the laser beam. By-products of the lasing process typically include oxygen and a brine solution of alkali chloride or halide (e.g. KCl, NaCl, LiCl or the like), as shown above in Equation 1.
Although COIL lasers are quite effective in battlefield situations, transportation and handling of the laser fuel chemicals can present logistics issues, particularly if the laser is mobile or stationed in a remote location (e.g. in space). To address these issues, many modem COILs include fuel regeneration systems (FRS) that effectively reprocess the laser byproducts into fuel that can be reused in subsequent laser operation. Typically, fluid regeneration systems include three separate processing cells, as shown in FIG. 1. As shown therein, a conventional FRS typically includes a chlor-alkali (“CA”) cell that electrolyzes salt received from the laser to produce a hydroxide, hydrogen and free chlorine as follows:2KCl+2H2O→2KOH+Cl2+H2  (2)The hydroxide formed at the CA cell is typically provided to an alkaline-peroxide (“AP”) cell that oxidizes water to produce BHP as follows:2KOH+H2O+½O2→H2O2+2KOH  (3A)Hydrogen obtained from the CA cell may be combined with oxygen in a fuel cell to form water, which is much less volatile than free hydrogen in accordance with the reaction:H2+½O2→H2O  (3B)When the process is complete, chlorine from the CA cell and BHP from the AP cell are provided to the laser for further consumption. The complete stoichemistry for this process is:2KCl+2H2O+O2→2KOH+H2O2+Cl2  (4)which is the inverse of Equation 1 above, except that the oxygen in Equation 4 can be in any electronic state. Accordingly, adding the mixture of two moles of alkali hydroxide and one mole of hydrogen peroxide (i.e. alkaline peroxide) to BHP that had been used in lasing restores the BHP to its original stoichiometry.
Although the use of a FRS does improve the battlefield logistics of operating a COIL, the three-cell nature of the FRS requires a relatively large amount of electrical energy to support the three separate reactions. Several attempts have been made to combine the various cells, but performance issues remain with many of these systems. U.S. Pat. No. 6,004,449 issued to Vetrovec on Dec. 21, 1999, for example, describes an electrolytic cell that includes a trickle bed cathode and a diaphragm for controlling liquid flow throughout the cell. Although this system contains fewer cells than most conventional FRS's, the system exhibits various manufacturability and performance issues relating to complexities of the trickle-bed cathode.
It therefore remains desirable to create a fuel regeneration system that improves the efficiency of the regeneration process. In addition, it is desirable to reduce or eliminate the need for one or more cells in the FRS to reduce the complexity of the system. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.